A microwave oven and automatic cooking system uses a food package provided with a noncontact IC tag storing information about a food contained in the food package, where the information about the food includes information about a method of heating the food and an amount of heat energy for cooking the food, the information about the amount of heat energy being expressed in a form of an absolute amount of heat energy. The microwave oven receives the food package and cooks the food contained in the food package. The microwave oven includes a reader that reads the information stored in the noncontact IC tag, and a ccontroller that controls the cooking of the food contained in the food package under optimum cooking conditions on the basis of the information read from the noncontact IC tag by the reader, the controller being programmed to automatically set an absolute amount of heat energy to be provided by the microwave oven on the basis of the information read by the reader, and set a heating time in accordance with an output capacity of the microwave oven and a type of the microwave oven so that the absolute amount of heat energy from the microwave oven conforms with the absolute amount of heat energy information read from the noncontact IC tag.